Implement Stripe and QBO payment flows for SMB client automation. Use this skill ANY TIME the user mentions payments, charging a client, Stripe, checkout, subscriptions, refunds, disputes, webhooks, invoice payment, payment links, PCI compliance, or syncing payments to QuickBooks. Also use when they say things like "how do I get paid," "set up billing," "client paid but QBO still shows open," "handle a refund," or "my webhook isn't firing." Covers Stripe checkout, webhook handling, QBO payment sync, subscriptions, refunds, and common failure modes.